The present invention relates to a prefabricated window system, and more particularly to a prefabricated window system having a main frame and other elements including a sill which are fabricated from extruded thermoplastic members.
Prefabricated windows are frequently used, both for new construction and replacement purposes, in order to provide high quality at a moderate cost. The desireable attributes of a prefabricated window are easier to state than to achieve. The window should be relatively inexpensive both to purchase and to install, but it should nevertheless offer excellent security against the elements. Furthermore the window should be attractive and sufficiently rugged to withstand abuse. Finally, these qualities should be present not only at the time of installation but for many years thereafter.
The S 771 (.TM.) prefabricated window system of Rehau Incorporated, having an office in Leesburg, Va., achieves the aforesaid qualities to an admirable degree. The S 771 window is described in a pending application, Ser. No. 06/929,303, filed Nov. 12, 1986, which is incorporated hereby by reference. Briefly, the window system disclosed in this application includes a rectangular main frame having a top frame portion, a bottom frame portion, and two side frame portions. The frame portions are made from extruded vinyl and all have the same cross-sectional configuration or profile except for features such as drainage channels which are fabricated after extrusion. The side frame portions provide channels for guiding two window sashes and a screen member, and since the top and bottom frame portions have the same cross-sectional configuration as the side frame portions such channels are also present in the top and bottom frame portions. Primarily to improve the appearance of the window, a snap-in decorative panel covers one of the window channels in the top frame portion. An extruded vinyl sill having closed internal compartments is provided at the bottom frame portion. The sill has resilient legs by which the sill is snap-connected to flanges which extend into the window channels of the bottom frame portion. The sill covers the window channels of the bottom frame portion.
In the window system of the aforesaid pending application, the screen channel of the bottom frame portion is exposed to the elements. While water can be drained by drilling a bore through the screen channel, it has been found that debris occasionally accumulates in the screen channel of the bottom frame portion to an undesirable degree. Unless such debris is cleared away, either by the rain or the homeowner, it may collect in uneven piles which prevent the screen member from being fully lowered. Thus the accumulated debris is not only unsightly, in extreme cases it may cause gaps at the bottom edge of the screen member and thus permit insects to enter the house.